1. Field of the Invention:
This invention relates generally to a paper sheet counting apparatus, and particularly to a device for preventing faulty counting of the paper sheets being handled in apparatus. Generally in a paper sheet counting apparatus, a bundle of paper sheets is charged in a holder which is movable between a depositing position and a counting position. Then, the holder is moved to the counting position in which the bundle of the paper sheets is counted. After the counting operation has been completed, the holder is returned back to the initial depositing position where the counted paper sheets aare removed ready for the next cycle of counting.
2. Prior Art:
In the prior art paper sheet counting apparatus, for instance in a bank note counting machine used in a bank, paper sheets charged in a holder positioned at a depositing position are detected by a detector, for example including a photoelectric element. The holder is then driven to swingably move to the counting position in response to a start signal generated by the detector. The counting operation is started after the holder is swung to the counting position. After completion of one cycle of counting operation, the holder is returned back to the initial charging position to be ready for the next cycle of counting. If the bundle of paper sheets is moved back to the initial depositing position together with the holder returning back to the depositing position when one cycle of counting operation is terminated, the detector again senses the bundle of paper sheets so that the next cycle of counting operation re-starts again. In order to eliminate the aforementioned risk, it has been proposed, by our co-pending Japanese Utility Model Application No. 18789/1978, to provide mechanical means to prevent only the bundle of paper sheets from being returned back to the initial depositing position even when the holder is retracted to the initial depositing position upon completion of one cycle of counting operation.
The device proposed by our co-pending application referred to above for preventing erroneous double-counting, will be described in detail hereinbelow.
Referring to FIG. 1 showing, in plan, a paper sheet counting machine provided with a device according to the preceding proposal for preventing double-counting, when the bundle of paper sheets 2 is loaded into a holder positioned at its initial or retracted position, as shown in FIG. 1, a light which is emitted from a light emitting element L1 and received by a photo-transistor P1 is shielded by the lower and forehand end of a bundle of paper sheets 2. A counting operation control circuit, not shown, connected with the photo-transistor P1 instructs the movement of the holder and controls the operation of the counting of the paper sheets from the bundle 2 in response to the change in output from the photo-transistor P1, whereupon the holder 1 is swung about an axis 3 in the direction shown by arrow 4 together with the bundle of paper sheets 2. During this movement of the holder, the bundle of paper sheets 2 passes a blocking piece, made, for example, of a leaf spring 5, while depressing the fore end of the leaf spring 5. (Reference should be made also to FIG. 2 showing the front view of the counting section of the device of FIG. 1.) Thus, the paper sheets are pressed on one of the suction heads 8 of a suction cylinder 7 rotating in the direction shown by arrow 6 while being clamped in-between the holder 1 and a clamping rod 12'. Since the suction heads 8 have suction ports (not shown) and rotate in the direction shown by arrow 9, paper sheets are sucked and turned over one by one from the bundle of paper sheet 2 to be counted. Reference numerals 10 and 11 designate, respectively, a guide plate and support plate for guiding the forehand end of the bundle of paper sheets 2 as the holder 1 swings.
The holder 1 is moved in the reverse direction to the arrow 4 to be returned to the initial position upon completion of one cycle of counting operation. However, the bundle of paper sheets 2 is blocked by the blocking piece 5 to be prevented from returning back to the initial position, ad shown in FIG. 2, so that the light emitted from the light emitting element L1 and received by the photo-transistor P1 is not shielded to prevent double-counting.
As described above, the device of the preceding proposal prevents double-counting by the provision of mechanical means. However, in this known device, the forehand free end of the resilient blocking piece must be positioned at a vertical position accurately and the spring force thereof must be delicately adjusted. If the positioning and adjustment of the spring force are not done pertinently, there is a possibility that a malfunction of the device would occur. In detail, if the forehand free end of the blocking piece 5 is positioned too low, the bundle of paper sheets 2 might not be blocked thereby to be restored to the initial position. If the spring force of the blocking piece 5 is too strong, the bundle of paper sheets 2 is raised upwards by the spring action of the blocking piece 5 to a position at which the lower forehand end of the bundle does not shield the light emitted from the light emitting element L1 and received by the photo-transistor P1. As a result, a signal for instructing the movement of the holder to start would not be generated. In addition, care must be taken so that the paper sheets 2 are not torn or damaged by the scratching action of the blocking piece 5 when the bundle of paper sheets 2 is returned to the initial position after the completion of counting operation. As will be apparent from the foregoing, the known device provided with mechanical means for preventing double-counting has various disdvantages, although it operates to attain the aimed objective.